4.3 Relational Databases and Normalisation

Question 1

Relations

Answer 1

Where data is held in tables in a relational database

Question 2

Normalisation

Answer 2

• A process used to come up with the best possible design for a database
• Tables should be organised so that data is not duplicated in the same table or in indifferent tables
• The structure should allow complex queries to be made

Question 3

3 stages of normalisation

Answer 3

1NF, 2NF, 3NF

Question 4

1NF

Answer 4

• Contains no repeating attributes or groups of attributes
• All attributes must be atomic - a single attribute cannot consist of 2 data items such as firstname and surname

Question 5

2NF

Answer 5

• 1NF and contains no partial dependencies
• Can only occur if the primary key is a composite key

Question 6

3NF

Answer 6

Contains no non-key dependencies

Question 7

Advantages of normalisation

Answer 7

• Easier to maintain and change
• No unnecessary duplication of data
• Data integrity is maintained
• Having smaller tables with fewer fields means faster searches and savings in storage